1. Field of the Invention
The present invention relates to a radio communication system which includes a centralized supervisory station and a plurality of terminal stations and repeater stations connected in series with each other by radio, or more particularly to an apparatus and a method for setting station-identifying information in a station within the communication system. A supervision/control device, which is provided in each of the terminal stations and repeater stations, performs a supervision/control processing according to a supervision/control signal transmitted from the centralized supervisory station and propagated in series through the stations.
The supervision/control signal, which includes station-identifying information (hereinafter called an ID number), is directed to a station having the ID number set exclusively for the station. Thus, when a station is added in the communication system or the ID number is changed for a station, for example, the ID number need be newly set in the supervision/control device. Accordingly an economical and reliable apparatus and method for setting the ID number in the supervision/control device is in great demand.
2. Description of the Related Art
FIG. 1 is a diagram illustrating a radio communication system.
Stations A and D, which are connected directly (by wire) to a centralized supervisory station by wire (e.g., telephone line) are called high-ranking terminal stations. Stations B and E, which are connected to the stations A and D, respectively by radio via repeater stations, are called a low-ranking terminal stations. A station B', which locates in the same network center as the station B and is connected directly (not via a repeater station) to a station C by radio, is called a high-ranking terminal station, while the station C is called a low-ranking terminal station.
In general, when subscribers communicate with each other in a communication system by wire or wireless (i.e., radio), a signal (e.g., audio or data signal) is transmitted from a subscriber through a subscriber's line to a network center and therefrom is transmitted through an exchange and a multiplexer provided in the network to a high-ranking terminal station (e.g., terminal station A). In the high-ranking terminal station, the aforesaid signal transmitted from the subscriber (hereinafter called a preliminary signal) is multiplexed with a supervisory/control signal sent from the centralized supervisor station.
In case of a radio communication system, the multiplexed signal is modulated by a carrier of radio frequency (e.g., 11 giga-hertz frequency band), i.e., converted into a radio frequency signal to be transmitted from an antenna. The radio frequency signal is received by the low-ranking terminal station (e.g., station B) through a repeater station.
The repeater station receives the radio frequency signal, separates the preliminary signal and the supervisory/control signal from the received signal and cheeks the ID number to see whether the supervision/control signal is directed to the station. If so, the repeater station performs supervision/control processing according to the signal and returns a response to the centralized supervisory station. Otherwise, it does not perform any processing or return a response and instead, multiplexes the separated preliminary signal and supervisory/control signal as originally was or with supervisory/control information of its own adding to the supervisory/control signal. Then, the repeater station converts the multiplexed signal into a radio-frequency signal to transmit from an antenna to a low-ranking terminal station or another repeater station.
A low-ranking terminal station, for example, receives the radio-frequency signal, separates the preliminary signal and the supervisory/control signal from the received radio-frequency signal to transfer the preliminary signal to a subscriber. In the same way as the repeater station, when the supervisory/control signal is directed to the terminal station itself, it performs the processing according to the supervisory/control signal and returns a response to the centralized supervisory station.
Thus, the supervisory/control signal is transmitted from the centralized supervisory station, bit-serially and in common to all the stations, through a high-ranking terminal station and a repeater station to a low-ranking terminal station. Accordingly, each station is required to have a function to determine whether the received supervisory/control signal is directed to the station itself.
To achieve the function, each station has a supervision/control device, which has an ID number of its own set therein for identifying itself, compares an ID number included in the received supervisory/control signal with the ID number of its own and, depending on a match/mismatch, determines whether the received supervisory/control signal is directed to the station.
FIG. 2 is a diagram illustrating the configuration of a terminal equipment, particularly of a high-ranking terminal station (e.g., station A in FIG. 1) that is connected by wire to the centralized supervisory station by wire, in which equipment the present invention is implemented.
A line switching unit 1 switches a regular line (CH1 or CH2) to an alternative line (SP) according to a control signal sent from a supervisory/control device (described later) when a failure occurs in one of the regular lines. A modem 2 modulates and demodulates the preliminary signal. A radio transceiver 3 multiplexes the preliminary signal modulated by the modem 2 and the supervisory/control signal and sends the multiplexed signal via the antenna as a radio signal. It also separates the preliminary signal and the supervisory/control signal from a radio signal received via the antenna and outputs the signals to the modem 2 and the supervisory/control device, respectively.
The system components enclosed by chain lines constitute the supervision/control device which the present invention relates, comprises a modem 4, a communication controller 5, a microprocessor unit (MPU) 6, a read-only memory (ROM) 7, a random access memory (RAM) 8, a multiplexer 9, a separator 10, a codec 11 and an input/output port (I/O) 12.
The ROM 7 stores a control program for controlling the operations of the supervision/control device. The MPU 6 controls the system components by executing instructions constituting the program stored in ROM 7. The RAM 8 temporarily stores data being processed by the system components.
The communication controller 5 converts the bit-serial supervision/control signal, which is input according to a protocol from the centralized supervisory station through the modem 4, into a parallel data signal to place the data on the system bus. It also converts the parallel data input from the system bus into a bit-serial data signal to send the signal through the modem 4 to the centralized supervisory station.
The I/O 12 receives status information (e.g., alarm signal) from the line switching unit 1, modem 2 and radio transceiver 3 and sends a control signal to the line switching unit 1, to command that a regular line (CH1 or CH2) be switched to the alternative line (SP).
A conventional supervision/control device was provided with a panel (not shown) having a setting board on which a jumper wire was placed to provide the ID number proper to the station. When a new station is installed in a communication system or when the panel fails, for example, the ID number need be newly set or re-set. In a conventional method, however, a customer engineer had to set the ID number manually at the site, even of an unmanned repeater station.
Therefore, it is a problem that the ID number setting work is time-consuming and troublesome. It is another problem that the ID number may be set erroneously, causing a trouble to the communication system.